Removal of smoke or other hazardous gases from enclosed spaces such as refinery tanks, tanker ships, commercial and naval vessels and mine shafts, require high volume, high head fans. These fans may be driven by electricity, water power of compressed air. There are some significant advantages in using compressed air. However, existing high power compressed fans are very noisy. This is because in the typical compressed air fan the exhaust air out of the turbine is moving at supersonic speed. Very often the personnel that are working in close proximity of such fans are exposed to a high pitch noise generated by the exhausting air. Such high pitch noise is usually uncomfortable to the persons exposed to it. Occupational safety laws, generally limit the time the worker could be exposed to a high level noise.
It is an objective of the present invention to provide a compressed air turbine driven fan which operates at substantially lower noise level than the noise generated by state of the art air turbine driven fans.